Social contract, because people can agree to a bad government as easily as to a good one.
Atticus explained in a way that the children will understand it. He thinks that the children convinced Mr. Cunningham that Atticus is an innoccent person who stands up to the Tom Robinson case. I think Atticus is wrong because the children are like defending him from the danger he's about to get in. His understand of a mob is realistic.
I read this book recently and I know it's correct. Hope this helps!
4 because it doesn't relate to the other 3 answers